Variable displacement gear pump

ABSTRACT

A variable displacement overlapping vane or gear pump including a pair of oppositely disposed rotors having overlapping vanes. The rotors are mounted in a housing having an inlet and outlet disposed along the track followed by the overlapping vanes. A drive ball is disposed between the rotors for driving one of the rotors directly, the other being driven by the interengaging vanes. A dish-shaped regulator located behind each rotor is angularly movably mounted within the housing, but is fixed against rotation with respect thereto. A control cam, eccentrically mounted on a drive shaft extending from the drive ball, can be adjusted to adjust the angular orientation of the regulator within the housing. The regulator in turn engages a rim on the rotor so that angular adjustment of the regulator results in angular adjustment of the rotor. A plurality of pins are mounted in the drive ball, one for each pair of overlapping vanes. Each pin extends between the vanes and is sufficiently large that the vanes continually engage only the pin during rotation of the rotors, regardless of the angular orientation of the rotors with respect to one another. This maintains generally constant the circumferential distance encompassed by the vanes on a circle generally dividing the space between the rotors, thereby preventing the vanes from jamming and breaking off. An alternative to employing the pins involves configurating the vanes in such a way that they do not expand the circumferential distance encompassed by the two vanes on the circle which divides the space between the two rotors.

States Patet [191 Caldwell Nov. 12, 1974 1 1 VARIABLE DISPLACEMENT GEAR PUMP [75] Inventor: Alan K. Caldwell, Big Rapids, Mich.

I [73] Assignee: Rewop Company, Grand Rapids,

. Mich.

221 Filed: Mar. 29, 1973 21 Appl. No.: 345,998

[52] [1.5. CI 418/16, 418/19, 418/193 [51] Int. Cl. FOlC 21/16 [58] Field of Search ..418/16,19, 22, 23,192, 418/193, 195

[56] References Cited UNITED STATES PATENTS 32.372 5/1861 Jones et al. 418/193 2,049,775 8/1936 Holmes...'. 418/16 2,962,864 12/1960 Van Cleve 418/22 3,101,700 8/1963 Bowdish 418/193 3,176,908 4/1965 Bowdish 418/193 3,277,792 10/1966 Stenerson 418/193 3,549,286 6/1967 Moriarity 418/193 Primary ExaminerC. J. Husar Attorney, Agent, or FirmPrice, l-leneveld, Huizenga & Cooper [57] ABSTRACT A variable displacement overlapping vane or gear pump including a pair of oppositely disposed rotors having overlapping vanes.'The rotors are mounted-in a housing having an inlet and outlet disposed along the track followed by the overlapping vanes. A drive ball is disposed between the rotors for driving one of the rotors directly, the other being driven by the interengaging vanes. A dish-shaped regulator located behind each rotor is angularly movably mounted within the housing, but is fixed against rotation with respect thereto. A control cam, eccentrically mounted on a drive shaft extending from the drive ball, can be ad'- justed to adjust the angular orientation of the regulator within the housing. The regulator in turn engages a rim on the rotor so that angular adjustment of the regulator results in angular adjustment of the rotor. A plurality of pins are mounted in the drive ball, one for each pair of overlapping vanes. Each pin extends between the vanes and is sufficiently large that the vanes continually engage only the pin during rotation of the rotors, regardless of the angular orientation of the rotors with respect to one another. This maintains generally constant the circumferential distance encompassed by the vanes on a circle generally dividing the space between the rotors, thereby preventing the vanes from jamming and breaking off. An alternative to employing the pins involves configurating the vanes in such a way that they do not expand the circumferential distance encompassed by the two vanes on the circle which divides the space between the two rotors.

50 Claims, 14 Drawing Figures VARIABLE DISPLACEMENT GEAR PUMP BACKGROUND OF THE INVENTION This invention relates to variable displacement pumps. Specifically, it relates to what might be called overlapping vane or gear pumps.

Variable displacement pumps operate by changing the volume of fluid which the pump can displace in a given cycle of operation. In a piston pump, this result would be achieved by changing the stroke of the piston. In sliding vane pumps, this result is achieved by changing the position of the track followed by the vanes either inwardly towards the vane rotor or outwardly away therefrom. The vanes in a sliding vane pump are slidably mounted in a central rotor and slide inwardly and outwardly with respect to the rotor as the pump cycles.

To my knowledge, no one has heretofore conceived a variable displacement pump of the overlapping vane or gear type. One prior art pump does employ a first rotor which is slotted and a second rotor which has vanes extending into these slots. However, only one of the rotors in this particular pump is angularly adjustable with respect to the other, thereby somewhat limiting the degree to which the displacement can be varied.

SUMMARY OF THE INVENTION The present invention constitutes a variable displacement overlapping vane or gear pump. A pair of rotors are rotatably mounted within a housing having a suitable inlet and outlet. Each of the rotors includes a plurality of vanes,'the vanes onone rotor extending towards the corresponding vanes on the other rotors and overlapping them. A drive means is operatively connected to at least one of the rotors for effecting rotation thereof. In one aspect of this invention, means are provided for variably adjusting the angular orientation of both of the rotors. One advantage of such a pump is that the pumping direction can be changed without changing the direction of rotation of the rotors. By angularly adjusting the rotors so they converge at the top rather than at the bottom, or vice versa, one changes the pumping direction of the pump.

An important feature of this invention is the provision of means for maintaining generally constant the circumferential distance encompassed by a given pair of overlapping vanes as the rotors are rotated. This aspect of the invention is applicable even when only one of the rotors is angularly adjustable with respect to the other. If two flat vanes simply overlap, neither of the rotors could be angularly adjusted with respect to the other. At the top and bottom of the pump, the overlapping vanes would be generally parallel to one another. However, at points in between, the vanes would tend to be disposed at an angle to one another. In effect, they would pry against one another and would want to increase the circumferential distance encompassed by the two vanes along a circle generally dividing the space between the two rotors. Since to increase the distance encompassed by two vanes would be to decrease the distance between adjacent vanes, the effect would be to either bind the pump up or to actually break the vanes off. By providing means for maintaining this circumferential distance generally constant, the problem of broken vanes and jammed pumps is eliminated.

One aspect of this invention involves achieving this constant distance by positioning a pin means between each pair of adjacent vanes. As the vanes adjust angularly with respect to one another, they simply change the point of contact with the pin means and they never come in contact with one another. They have no opportunity to pry against one another.

This end can also be achieved by shaping the overlapping vanes properly. One way to achieve this result is to shape one of the vanes convexly and leave the other flat. In effect, the flat vane simply changes position along the convex surface, the effect being comparable to that of the vanes changing position about a pin means disposed therebetween. Another manner of shaping the vanes is to curve them such that they slidably engage one another at all times along their correspondingly curved surfaces.

Another significant feature of this invention which facilitates the angular adjustment of the rotors is the provision of a regulator means interposed behind at least one of the rotors, between the rotor and the housing. The regulator is fixed against rotation with respect to the housing, but is movable angularly therein. While the rotor is rotatable with respect to the regulator, the regulator engages the rotor in such a manner that the angular adjustment of the regulator effects angular adjustment of the rotor.

Control means are operably associated with the regulator for facilitating its angular adjustment.

Finally, another feature of this invention is the unique drive means for the pump. A drive ball is disposed generally between the two rotors. The rotors are generally dish-shaped, semispherical members. At least one of the rotors includes grooves which correspond to grooves in the ball. A bearing member is disposed in I each set of facing grooves so that the drive ball and the rotor rotate together. Yet, the grooves are sufficiently long that the angular orientation of the rotor can be adjusted with respect to the drive ball. The drive ball thereby drives one of the rotors, and the other rotor is driven by the interengaging vanes.

These and other objects, advantages and features of the invention will be more fully appreciated and understood by reference to the written specification and appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partially cross-sectional, elevational view of the variable displacement pump;

FIG. 2 is the same view as FIG. 1, but with the rotors and regulators being shown in an angularly different position with respect to the housing;

. FIG. 3 is a cross-sectional view taken along plane III- III of FIG. 1;

FIG. 4 is a fragmentary view of the rotors with only one set of vanes shown, generally at the bottom of the pump as viewed in FIG. 2;

FIG. 5 is a fragmentary showing of the rotors with only one set of vanes being shown, generally at the top of the pump as viewed in FIG. 2;

FIG. 6 is a partiallycross-sectional view comparable to the cross-sectional view of FIG. 3, but with the drive ball being shown whole and with one of the two rotors being completely removed;

FIG. 7 is a cross-sectional view comparable to that of FIG. 6 with the drive ball and rotor shown'in FIG. 6 removed;

FIG. 8 is an elevational view of the regulator and cooperating control cam;

FIG. 9 is an elevational view of the regulator and cooperating control cam with the control cam in a different position than that shown in FIG. 8;

FIG. 10 is an elevational view of two rotors showing only one set of corresponding vanes, the vanes being of an alternative configuration;

FIG. 11 is a view comparable to that of FIG. 4 only including the vanes of FIG. 10;

FIG. 12 is a showing comparable to that of FIG. only showing the vanes of FIG.

FIG. 13 is a view comparable to FIG. 10 showing yet another alternative vane configuration; and

FIG. 14 is a view comparable to FIG. 4 only showing the vanes of FIG. 13.

DESCRIPTION OF THE PREFERRED EMBODIMENT In the preferred embodiment, the rotors are rotatably mounted in oppositely disposed fashion, on either side of a rotatably mounted drive ball 30, within a housing 10 having an appropriate inlet 11 and outlet 12 (FIGS. 1, 2, and 3). The only distinction between lefthand rotor 20 and right-hand rotor 20a is that righthand rotor 20a is driven directly by drive ball 30 whereas left-hand rotor 20 is indirectly driven by drive ball 30 through the overlapping interengaging vanes 21 of rotors 20 and 20a. As used herein, the number 20 could refer to either of the rotors whereas the number 20a refers only to the rotor driven by drive ball 30.

A plurality of pins 40 extend radially outwardly from drive ball 30, one pin 40 being interposed between each pair of overlapping vanes 21 as rotors 20 rotate. Regardless of the angular orientation of rotors 20 (compare FIGS. 1 and 2), vanes 21 contact only pins 40 so that the circumferential distance encompassed by a given pair of vanes on a circle dividing the space between the two rotors remains generally constant as the rotors rotate. Rotors 20 can be adjusted angularly with respect to one another throughthe operation of regulators 50 which engage the peripheral rim 23 of rotors 20. Each regulator 50 is fixed against rotation with respect to housing 10, but is movable therein so that it can be adjusted angularly. Angular adjustment of regulator 50 is achieved with a control cam 60 which is eccentrically mounted on the drive shaft 31 which extends from each side of drive ball 30.

Housing 10 is a metal casting with an inlet 11 and an outlet 12 drilled into opposite sides thereof (FIGS. 3 and 7). It includes a circular track 13 upon which the vanes 21 of rotors 20 ride. Track 13 is sufficiently wide that it will be engaged by the rims 23 of rotors 20 even when rotors 20 are angularly adjusted to their extreme position as shown in FIG. 2. Track 13 does include a pair of oppositely disposed grooves 16 therein. Each groove extends generally from the point of maximum displacement between the rotors 20 to the point of minimum displacement therebetween (FIG. 7). As the pump is depicted in these drawings, the grooves 16 extend generally from the top to the bottom of track 13. Only the uppermost and lowermost portions of track 13 j are completely closed. Inlet 11 and outlet 12 can be located generally at any point along the length of their respective grooves 16, but are preferably located generally at the center of the grooves 16.

When the rotors 20 are oriented as shown in FIG. 2, they are at their point of minimum displacement generally at the bottom of track 13. Assuming the vanes are moving clockwise, the displacement between the rotors 20 begins to increase as one moves up track 13. This increasing displacement draws fluid in through inlet 11. Grooves 16 communicate with inlet 11 so that the vanes 21 draw fluid in as soon as displacement begins to increase and until vanes 21 reach generally the top of track 13 at which point groove 16 terminates and vanes 21 have reached their point of maximum displacement. As the vanes pass the top of track 13, the displacement between rotors 20 begins to decrease, thereby forcing fluid out from between each adjacent pair of vanes 21, into grooves 16 and out through outlet 12. This action continues until the vanes reach the bottom end of groove 16 on the outlet side of housing 10.

Housing 10 also includes a drive shaft opening 17 through each side thereof, each opening being located from the circle dividing track 13 (FIGS. 1 and 7). Opening 17 allows the ends of drive shaft 31 to pass through housing 10. Located on the inner surface of housing 10, generally on opposite sides of drive shaft opening 17, are guide grooves 14. Guide grooves 14 are located in the plane which passes through the points of maximum and minimum displacement of rotors 20 and which is perpendicular to the circle dividing track 13. Guide grooves 14 provide a means for guiding regulators 50 as they are adjusted angularly within housing Each of the rotors 20 is a casting or stamping made of metal. Each rotor 20 comprises a semispherical dishshaped portion which conforms to the surface of drive ball 30 and which is contiguous therewith (FIG. 1). A rim 23 extends from dish portion 22, generally away from the drive ball 30. Joined to and projecting outwardly from rim 23 are the plurality of vanes 21. The vanes 21 are somewhat arcuately shaped in elevation so that they occupy the space between the surface of track 13 of housing 10 and the surface of drive ball 30. There are an equal number of vanes 21 on each rotor 20 and the corresponding vanes 21 extend towardsand overlap one another. In the embodiment shown in FIGS. 1 through 6, the vanes 21 do not actually touch one another, but rather engage the pin 40 which is disposed therebetween. I

The only difference between rotor 20a and the lefthand rotor 20, as viewed in FIG. 1, is that rotor 20a includes a pair of spaced grooves 26a on its interior surface, the grooves being shown hidden in FIG. 1. Groove 26a correspond to the oppositely opening spaced grooves 32 in drive ball 30 (FIG. 6). Each of the facing grooves 26a and 32 include a ball bearing 33 located therein which fixes rotor 20a against rotation with respect to drive ball 30. Groove 26a and groove 32 are sufficiently long that ball bearing 33 is free to move a sufficient distance along the length thereof to allow rotor 20a to be adjusted angularly with respect to drive ball 30.

Each rotor 20 includes an opening 24 therein through which a drive shaft 31 can pass. Opening 24 is somewhat larger than the cross section of drive shaft 31 so that rotor 20 can be angularly adjusted about the surface of drive ball 30.

Drive ball 30 is a circular ball formed of metal or the like. It includes a drive shaft 31 extending outwardly from each opposite side thereof (FIGS. 1 and 2). Grooves 32 are machined into the surface of ball 30 at appropriate quadrantly spaced points (FIG. 6). They are necessary on only one side of drive ball 50 since it is only necessary that one of the rotors be driven.

Projecting radially from drive ball in a plane perpendicular to the axis of drive shaft 31 are the plurality of pins 40. Each pin is embedded in drive ball 30 (FIG. 3) and extends therefrom a distance approximately equal to the radial depth of vanes 21. In this manner, the passage of fluid between cooperating vanes 21 is minimized. Each pin 40 is made of metal and is preferably generally circular in cross section. Pins 40 can be inserted in drive ball 30 by swaging.

The regulators which effect angular adjustment of rotors 20 comprise generally dish-shaped semispherical members stamped or cast of metal. Each regulator 50 includes a pair of fins 52 projecting outwardly from its outer surface and into the grooves 14 in housing 10 (FIG. 1). Fins 52 are a good deal shorter than grooves 14 so that each regulator 50 is movable within housing 10. This allows angular adjustment of regulator 50 with respect to housing 10. However, the interengagement of fins 52 and grooves 14 prevents rotation of regulator 50 with respect to housing 10. Regulator 50 corresponds in configuration to the dish-shaped portion 22 of rotor 20 such that the perimeter of regulator 50 engages the rim 23 of rotor 20. Accordingly, when regulator 50 is moved, i.e., angularly adjusted, within housing 10, it also effects angular adjustment of rotor 20 (compare FIGS. 1 and 2).

Each regulator 50 includes an opening 51 therethrough to allow drive shaft 31 to pass therethrough. Opening 51 has an additional function, and is therefore generally rectangular in configuration (see FIGS. 8 and 9). Opening 51 performs a control function in conjunction with a control cam 60. Control cam is eccentrically mounted on drive shaft 31. Rectangular opening 51 is shaped such that cam 60 engages the perimeter of opening 51, particularly along the top and bottom edges thereof. Control cam 60 includes a crank handle 62 thereon which can be manually operated to change the position of cam 60 with respect to opening 51 in the manner illustrated by comparing FIGS. 8 and 9. Cam 60 is rotatably mounted on shaft 31, but can be held against rotation with respect to shaft 3l so that once cam 60 is adjusted, it does not rotate when the shaft 31 rotates. Provision of a specific means for preventing cam 60 from rotating when shaft '31 rotates is well within the skill of one skilled in the art. When cam 60 is oriented in the manner shown in FIG. 8, rotors 20 are angularly disposed in the manner shown in FIG. 2, the minimum displacement beingtowards the bottom of housing 10. When cam 60 is rotated to the position shown in FIG. 9, the pump will not displace any fluid since the rotors 20 will be oriented in the position shown in FIG. 1.

In the embodiment described above, pins 40 are used to maintain constant the circumferential distance encompassed by each pair of overlapping vanes 21 on a circle which generally divides the space between rotors 20. FIG. 2 shows the manner in which vanes 21 reorient themselves with respect to pin 40 at a point generally between the maximum and minimum displacement of the pump. FIG. 4 shows the orientation of vanes 21 with respect to pins 40 at the point of minimum displacement between rotors20 and FIG. 5 shows the orientation of vanes 21 with respect to pins 40 at the point of maximum displacement between rotors 20.

FIGS. 10-14 show two alternative means for maintaining constant the circumferential distance encompassed by each pair of vanes 21 as rotors 20 are rotated. FIG. 10 is comparable to FIG. 2, except that only the rotors 20 are shown and only one pair of vanes is shown. In the FIG. 10 embodiment, one of the rotors 20 has flat vanes 21. However, the other rotor 20 has vanes which have a convex surface. The flat vane 21 engages the convex vane 70 along its convex surface. In effect, vane 21 reorients itself along the convex sur' face of convex vane 70 in much the same manner as the vanes 21 in the FIG. 4 and FIG. 5 embodiments reorient themselves about the central pin 40. In FIGS. 11 and 12, the vanes 70 and 21 are shown interengaging at the points of minimum and maximum displacement of the pump respectively.

In the embodiment shown in FIG. 13, a view comparable to that of FIG. 10, a pair of curved vanes are provided. Vanes 80 are curved in such a fashion that they continually slidably engage along their curved surfaces, thereby eliminating prying of one vane away from another. FIG. 14 shows the relationship of the vanes 80 at the point of minimum displacement of pump 1. g

The operation of pump 1 is basically the same regardless of the particular means used for maintaining constant the circumferential distance encompassed by each pair of vanes. Basically, pump 1 will pump no fluid when rotors 20 are in the position shown in FIG. 1. The rotors 20 can be thus positioned by rotating each control cam 60 to the position shown in FIG. 9. Either one or both of the rotors 20 can be angularly adjusted with respect to the other by changing the orientation of control cam 60 with respect to drive shaft 31. Once either of the rotors 20 is oriented angularly with respect to the other, pump 1 will pump. When each control cam 60 is rotated to the position shown in FIG. 8, the rotors 20 will be oriented in the position shown in FIG. 2. Assum ing the vanes are rotated in a clockwise position, pump 1 will pump from inlet 11 to outlet 12 (FIG. 3) when rotors 20 are oriented as shown in FIG. 2. Actually, the terms inlet and outlet are not entirely appropriate since by merely rotating control cam 60 from the position shown in FIG. 8, one could make port 11 the outlet and port 12 the inlet. As viewed in FIG. 2, the top of track 13 would become the point of minimum displacement whereas the bottom of track 13 would become the point of maximum displacement. Thus, pump 1 is readily reversible even when drive shaft 31 is continuously driven in the same direction of rotation.

Of course, it will be understood that the above is merely a preferred embodiment of the invention and that various changes and alterations can be made thereof without departing from its spirit and broader aspects.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A variable displacement pump comprising: a housing having a pair of ports to provide an inlet and anoutlet; a pair of generally oppositely disposed rotors rotatably mounted in said housing; each of said rotors including a plurality of vanes, the vanes on one rotor corresponding to those on the other rotor, said corresponding vanes extending towards one another and generally overlapping one another; drive means operatively connected to at least one of said rotors for effecting rotation thereof; means for variably adjusting the angular orientation of at least one of said rotors with respect to the other whereby the displacement of said pump can be varied; means for maintaining generally constant the circumferential distance encompassed by a given pair of said corresponding vanes on the circumference of a circle dividing equally the space between said two rotors whereby, regardless of said angular orientation of-said rotors with respect to one another, said vanes do not bind against one another.

2. The variable displacement pump of claim 1 comprising: said drive means being disposed generally between said rotors; said means for maintaining generally constant the circumferential distance encompassed by a given pair of said corresponding vanes comprising pin means extending radially from said drive means and being disposed between each corresponding overlapping pair of vanes and generally contacting both whereby regardless of said angular orientation of said rotors with respect to one another, said vanes contact only said pin means as said rotors are rotated.

3. The variable displacement pump of claim 2 in which said pin means comprises: a pin having a generally circular cross section.

4. The variable displacement pump of claim 3 in which said pin is at least as deep as said vanes in a radial direction.

5. The variable displacement pump of claim 1 in which said drive means includes a drive ball located generally between said rotors; each said rotors comprising a generally dish-shaped member generally contiguous with said drive ball; said drive ball and said one of said rotors operatively connected thereto including oppositely disposed grooves which open towards one another; each set of oppositely disposed grooves including a bearing means disposed therein whereby said one rotor is fixed against rotation with said ball and thereby rotates with said drive ball when said drive ball is rotated.

6. The variable displacement pump of claim 5 in which said means for variably adjusting the angular orientation of at least one of said rotors with respect to the other comprises: a generally dish-shaped, regulator movably mounted in said housing and disposed between said one angularly adjustable rotor and said housing; said regulator engaging generally the perimeter of said one angularly adjustable rotor, said one angularly adjustable rotor being rotatable with respect to said regulator and said regulator being fixed against rotation with respect to said housing; control means associated with said regulator for facilitating angular movement of said regulator within said housing whereby the angle of orientation of said one angularly adjustable rotor with respect to the other rotor is varied.

7. The variable displacement pump of claim 6 in which said drive means includes a drive shaft passing through said one angularly adjustable rotor, through said regulator and through said housing; said one angularly adjustable rotor including an opening for said drive shaft, said opening being larger than the cross section of said drive shaft whereby said one angularly adjustable rotor can be adjusted angularly with respect to said drive shaft; said regulator including an opening larger than the cross section of said drive shaft; said control means including a cam eccentrically mounted on said drive shaft and engaging the perimeter of said opening in said regulator whereby rotation of said cam means with respect to said drive shaft effects angular adjustment of said regulator and said one angularly adjustable rotor.

8. The variable displacement pump of claim 7 in which said regulator is fixed against rotation with respect to said housing by means of a fin projecting therefrom towards said housing, said housing including a groove receiving said fin, said groove being longer than the length of said fin whereby said fin is free to slide in said groove and said regulator is thereby angularly adjustable.

9. The variable displacement pump of claim 1 in which said means for variably adjusting the angular orientation of at least one of said rotors comprises: regula tor means movably mounted in said housing, disposed between said one angularly adjustable rotor and said housing; said regulator means engaging said one angularly adjustable rotor and being fixed against rotation with respect to said housing, said one angularly adjustable rotor being free to rotate with respect to said regulator means; control means associated with said regulator means for facilitating angular adjustment of said regulator means within said housing whereby the angular orientation of said one angularly adjustable rotor is also adjusted.

10. The variable displacement pump of claim 9 in which said regulator means comprises: a generally dishshaped, regulator movably mounted in said housing and disposed between said one rotor and said housing; said drive means including a drive shaft passing through said one angularly adjustable rotor, through said regulator and through said housing; said one angularly adjustable rotor including an opening for said drive shaft, said opening being larger than the cross section of said drive shaft whereby said one angularly adjustable rotor can be adjusted angularly with respect to said drive shaft; said regulator including an opening larger than the cross section of said drive shaft; said control means including a cam eccentrically mounted on said drive shaft and engaging the perimeter of said opening in said regulator whereby rotation of said cam means with respect to said drive shaft effects angular adjustment of said regulator and said one angularly adjustable rotor.

11. The variable displacement pump of claim 10 in which said regulator means is a generally dish-shaped, member engaging generally the perimeter of said rotor.

which said regulator is fixed against rotation with respect to said housing by means of a fin projecting therefrom towards said housing, said housing including a groove receiving said fin, said groove being longer than the length of said fin whereby said fin is free to slide in said groove and said regulator is thereby angularly ad justable.

14. The variable displacement pump of claim 1 in which there are means for variably adjusting the angular orientation of both said rotors with respect to one another.

15. A variable displacement pump comprising: a housing having a pair of ports to provide an inlet and an outlet; a pair of generally oppositely disposed rotors rotatably mounted in said housing; each of said rotors including a plurality of vanes, the vanes on one rotor corresponding to those on the other rotor, said corresponding vanes extending towards one another and generally overlapping one another; drive means operatively connected to at least one of said rotors for effecting rotation thereof; means for variably adjusting the angular orientation of at least one of said rotors with respect to the other whereby the displacement of said pump can be varied; said vanes being shaped such that they maintain generally constant the circumferential distance encompassed by a given pair of vanes on the circumference ofa circle dividing equally the space between the two rotors while still maintaining continual contact for effecting a seal between the vanes.

16. The variable displacement pump of claim in which in each overlapping pair of vanes, one of said vanes is generally flat while the other thereof is convexly shaped, with its convex surface engaging said flat vane.

17. The variable displacement pump of claim 15 in which both vanes for each overlapping pair of vanes are generally curved in configuration, said vanes slidably engaging one another along the curved surfaces thereof.

18. The variable displacement pump of claim 15 in which said drive means includes a drive ball located generally between said rotors; each said rotors comprising a generally dish-shaped member generally contiguous with said drive ball; said drive ball and said one of said rotors operatively connected thereto including oppositely disposed grooves which open towards one another; each set of oppositely disposed grooves including a bearing means disposed therein whereby said one rotor is fixed against rotation with said ball and thereby rotates with said drive ball when said drive ball is rotated. 7

19. The variable displacement pump of claim 15 in which said means for variably adjusting the angular orientation of at least one of said rotors comprises: regulator means movably mounted in said housing, disposed between said one angularly adjustable rotor and said housing; said regulator means engaging said one angularly adjustable rotor and being fixed against rotation with respect to said housing, said one angularly adjustable rotor being free to rotate with respect to said regu-- lator means; control means associated with said regulator means for facilitating angular adjustment of said regulator means within said housing whereby the angular orientation of said one angularly adjustable rotor is also adjusted.

20. The variable displacement pump of claim 19 in which said regulator means comprises: a generally dishshaped, regulator movably mounted in said housing and disposed between said one rotor and said housing; said drivemeans including a drive shaft passing through said one angularly adjustable rotor, through said regulator and through said housing; said one angularly adjustable rotor including an opening for said drive shaft, said opening being larger than the cross section of said drive shaft whereby said one angularly adjustable rotor can be adjusted angularly with respect to said drive shaft; said regulator including an opening larger than the cross section of said drive shaft; said control means including a cam eccentrically mounted on said drive shaft and engaging the perimeter of said opening in said regulator whereby rotation of said cam means with respect to said drive shaft effects angular adjustment of said regulator and said one angularly adjustable rotor.

21. The variable displacement pump of claim 20 in which said regulator means is a generally dish-shaped member engaging generally the perimeter of said'rotor.

22. The variable displacement pump of claim 21 in which said drive means includes a drive ball, said rotor being a generally dish-shaped, member which is generally contiguous with said drive ball but which includes a rim projecting away from said drive ball generally at the perimeter of said rotor, said regulator being generally contiguous with the exterior of said rotor and engaging said rim thereof.

23. The variable displacement pump of claim 22 in which said regulator is fixed against rotation with respect to said housing by means of a tin projecting therefrom towards said housing, said housing including a groove receiving said fin, said groove being longer than the length of said fin whereby said fin is free to slide in said groove and said regulator is thereby angularly adjustable.

24. The variable displacement pump of claim 15 in which there are means for variably adjusting the angular orientation of both said rotors with respect to one another.

25. A variable displacement pump comprising: a housing having a pair of ports to provide an inlet and an outlet; a pair of generally oppositely disposed rotors rotatably mounted in said housing; each of said rotors including a plurality of vanes, the vanes on one rotor corresponding to those on the other rotor, said corresponding vanes extending towards one another and generally overlapping one another; drive means operatively connected to at least one of said rotors for effecting rotation thereof; means for variably adjusting the angular orientation of at least one of said rotors with respect to the other whereby the displacement of said pump can be varied; regulator means movably mounted in said housing, disposed between said one angularly adjustable rotor and said housing; said regulator means engaging said one angularly adjustable rotor and being fixed against rotation with respect to said housing, said one angularly adjustable rotor being free to rotate with respect to said regulator means; control means associated with said regulator means for facilitating angular adjustment of said regulator means within said housing whereby the angular orientation of said one angularly adjustable rotor is also adjusted.

26. The variable displacement pump of claim 25 in which said regulator means comprises: a generally dishshaped, regulator movably mounted in said housing and disposed between said one rotor and said housing; said drive means including a drive shaft passing through said one angularlyadjustable rotor, through said regulator and through said housing; said one angularly adjustable rotor including an opening for said drive shaft, said opening being larger than the cross section of said drive shaft whereby said one angularly adjustable rotor can be adjusted angularly with respect to said drive shaft; said regulator including an opening larger than the cross section of said drive shaft; said control means including a cam eccentrically mounted on said drive shaft and engaging the perimeter of said opening in said regulator whereby rotation of said cam means with respect to said drive shaft effects angular adjustment of said regulator and said one angularly adjustable rotor.

27. The variable displacement pump of claim in which: said drive means includes a drive ball, said rotor being a generally dish-shaped, member which is generally contiguous with said drive ball but which includes a rim projecting away from said drive ball generally at the perimeter of said rotor, said regulator being generally contiguous with the exterior of said rotor and engaging said rim thereof.

28. The variable displacement pump of claim 27 in which said regulator is fixed against rotation with respect to said housing by means of a fin projecting therefrom towards said housing, said housing including a groove receiving said fin, said groove being longer than the length of said fin whereby said fin is free to slide in said groove and said regulator is thereby angularly adjustable.

29. The variable displacement pump of claim in which: there are two said regulators, one for each said rotor, each of said rotors being angularly adjustable by means of said regulators.

30. A variable displacement pump comprising: a housing having a pair of ports to provide an inlet and an outlet; a pair of generally oppositely disposed rotors rotatably mounted in said housing; each of said rotors including a plurality of vanes, the vanes on one rotor corresponding to those on the other rotor, said corre sponding vanes extending towards one another and generally overlapping one another; drive means operatively connected to at least one of said rotors for effecting rotation thereof; said drive means including a drive ball located generally between said rotors; each said rotors comprising a generally dish-shaped member generally contiguous with said drive ball; said drive ball and said one of said rotors operatively connected thereto including oppositely disposed grooves which open towards one another; each set of oppositely disposed grooves including a bearing means disposed therein whereby said one rotor is fixed against rotation with said ball and thereby rotates with said drive ball when said drive ball is rotated; said other rotor being rotatably driven by the interengagement of said vanes of said one rotor which operably engage said vanes of said other rotor.

31. The variable displacement pump of claim 30 in which there are means for variably adjusting the angular orientation of at least one of said rotors with respect to the other whereby the displacement of said pump can be varied.

32. The variable displacement pump of claim 31 in which said means for variably adjusting the angular orientation of at least one of said rotors with respect to the other comprises: a generally dish-shaped, regulator movably mounted in said housing and disposed between said one angularly adjustable rotor and said housing; said regulator engaging generally the perimeter of said one angularly adjustable rotor, said one angularly adjustable rotor being rotatable with respect to said regulator and said regulator being fixed against rotation with respect to said housing; control means associated with said regulator for facilitating angular move ment of said regulator within said housing whereby the angle of orientation of said one angularly adjustable rotor with respect to the other rotor is varied.

33. The variable displacement pump of claim 32 in which said drive means includes a drive shaft passing through said one angularly adjustable rotor, through said regulator and through said housing; said one angularly adjustable rotor including an opening for said drive shaft, said opening being larger than the cross section of said drive shaft whereby said one angularly adjustable rotor can be adjusted angularly with respect to said drive shaft; said regulator including an opening larger than the cross section of said drive shaft; said control means including a cam eccentrically mounted on said drive shaft and engaging the perimeter of said opening in said regulator whereby rotation of said cam means with respect to said drive shaft effects angular adjustment of said regulator and said one angularly adjustable rotor.

34. The variable displacement pump of claim 33 in which said regulator is fixed against rotation with respect to said housing by means of a fin projecting therefrom towards said housing. said housing including a groove receiving said fin, said groove being longer than the length of said fin whereby said fin is free to slide in said groove and said regulator is thereby angularly adjustable.

35. A variable displacement pump comprising: a housing having a pair of ports to provide an inlet and an outlet; a pair of generally oppositely disposed rotors rotatably mounted in said housing; each of said rotors including a plurality of vanes, the vanes on one rotor corresponding to those on the other rotor, said corresponding vanes extending towards one another and generally overlapping one another; drive means operatively connected to at least one of said rotors for effecting rotation thereof; means for variably adjusting the angular orientation of each said rotor with respect to the other whereby the displacement of said pump can be varied.

36. The variable displacement pump of claim 35 in which said means for adjusting for each said rotor comprises: regulator means for each said rotor movably mounted in said housing, disposed between each said rotor and said housing; said regulator means engaging said rotor and being fixed against rotation with respect to said housing, said rotor being free to rotate with respect to said regulator means; control means associated with said regulator means for facilitating angular adjustment of said regulator means within said housing whereby the angular orientation of said rotor is also adjusted.

37. The variable displacement pump of claim 36 in which said regulator means comprises: a generally dishshaped, regulator movably mounted in said housing and disposed between said one rotor and said housing; said drive means including a drive shaft passing through said one angularly adjustable rotor, through said regulator and through said housing; said one angularly adjustable rotor including an opening for said drive shaft, said opening being larger than the cross section of said drive shaft whereby said one angularly adjustable rotor can be adjusted angularly with respect to said drive shaft; said regulator including an opening larger than the cross section of .said drive shaft; said control means including a cam eccentrically mounted on said drive shaft and engaging the perimeter of said opening in said regulator whereby rotation of said cam means with respect to said drive shaft effects angular adjustment of said regulator and said one angularly adjustable rotor.

38. The variable displacement pump of claim 37 in which said drive means includes a drive ball, said rotor being a generally dish-shaped, member which is generally contiguous with said drive ball but which includes a rim projecting away from said drive ball generally at the perimeter of said rotor, said regulator being generally contiguous with the exterior of said rotor and enwhich said regulator is fixed against rotation with respect to said housing by means of a fin projecting therefrom towards said housing, said housing including a groove receiving said fin, said groove being longer than the length of said fin whereby said fin is free to slide in said groove and said regulator is thereby angularly adjustable.

40. The variable displacement pump of claim 36 in which said drive means includes a drive ball, said rotor being a generally dish-shaped, member which is generally contiguous with said drive ball but which includes a rim projecting away from said drive ball generally at the perimeter of said rotor, said regulator being generally contiguous with the exterior of said rotor and engaging said rim thereof.

41. A variable displacement pump comprising a housing having a pair of ports to provide an inlet and an outlet; a pair of generally oppositely disposed rotors rotatably mounted in said housing; each of said rotors including a plurality of vanes, the vanes on one rotor corresponding to those on the other rotor, said corresponding vanes extending towards one another and generally overlapping one another; drive means operatively connected to at least one of said rotors for effecting rotation thereof; means for variably adjusting the angular orientation of at least one of said rotors with respect to the other, from a point at which said rotors are generally parallel in either direction on either side of this point whereby the displacement of said pump can be varied and whereby the direction of flow of fluid in said pump can be reversed without reversing the direction of rotation of said rotors.

42. The variable displacement pump of claim 41 in which said means for variably adjusting the angular orientation of at least one of said rotors comprises regulator means movably mounted in said housing, disposed between said one angularly adjustable rotor and said housing; said regulator means engaging said one angularly adjustable rotor and being fixed against rotation with respect to said housing, said one angularly adjustable rotor being free to rotate with respect to said regulator means; control means associated with said regulator means for facilitating angular adjustment of said regulator. means within said housing whereby the angular orientation of said one angularly adjustable rotor is also adjusted.

43. The variable displacement pump of claim 42 in which said regulator means comprises a generally dishshaped, regulator movably mounted in said housing and disposed between said one rotor and said housing; said drive means including a drive shaft passing through said one angularly adjustable rotor, through said regulator and through said housing; said one angularly adjustable rotor including an opening for said drive shaft, said opening being larger than the cross section of said drive shaft whereby said one angularly adjustable rotor can be adjusted angularly with respect to said drive shaft; said regulator including an opening larger than the cross section of said drive shaft; said control means including a cam eccentrically mounted on said drive shaft and engaging the perimeter of said opening in said regulator whereby rotation of said cam means with respect to said drive shaft effects angular adjustment of said regulator and said one angularly adjustable rotor.

44. The variable displacement pump of claim 43 in which said regulator means is a generally dish-shaped, member engaging generally the perimeter of said rotor.

45. The variable displacement pump of claim 44 in which said drive means includes a drive ball, said rotor being a generally dish-shaped, member which is generally contiguous with said drive ball but which includes a rim projecting away from said drive ball generally at the perimeter of said rotor, said regulator being generally contiguous with the exterior of said rotor gaging said rim thereof.

46. The variable displacement pump of claim 45 in which said regulator is fixed against rotation with respect to said housing by means of a fin projecting therefrom towards said housing, said housing including a groove receiving said fin, said groove being longer than the length of said fin whereby said fin is free to slide in said groove and said regulator is thereby angularly adjustable, and said groove being positioned such that said regulator can be moved to either side of a point at which'said one angularly adjustable rotor is parallel to the other. I

47. The variable displacement pump of claim 41 in which said regulator means is a generally dish-shaped, member engaging generally the perimeter of said rotor.

and en- 48. The variable displacement pump of claim 47 in which said drive means includes a drive ball, said rotor. being a generally dish-shaped, member which is gener-' ally contiguous with said drive ball but which includes a rim projecting away from said drive ball generally at the perimeter of said rotor, said regulator being generally contiguous with the exterior of said rotor and engaging said rim thereof.

49. The variable displacement pump of claim 48 in which said regulator is fixed against rotation with respect to said housing by means of a fin projecting therefrom towards said housing, said housing including a groove receiving said fin, said groove being longer than the length of said fin whereby said fin is free to slide in said groove and said regulator is thereby angularly adjustable, and said groove being positioned such that said regulator can be moved to either which said one angularly adjustable rotor is parallel to the other.

50. The variable dis lacement pump of claim 41 which includes means fbr maintaining generally constant the circumferential distance encompassed by a given pair of said corresponding vanes on the circumference of a circle dividing equally the space between said two rotors whereby, regardless of said angular orientation of said rotors with respect to one another, siad vanes do not bind against one another.

side of a point at. 

1. A variable displacement pump comprising: a housing having a pair of ports to provide an inlet and an outlet; a pair of generally oppositely disposed rotors rotatably mounted in said housing; each of said rotors including a plurality of vanes, the vanes on one rotor corresponding to those on the other rotor, said corresponding vanes extending towards one another and generally overlapping one another; drive means operatively connected to at least one of said rotors for effecting rotation thereof; means for variably adjusting the angular orientation of at least one of said rotors with respect to the other whereby the displacement of said pump can be varied; means for maintaining generally constant the circumferential distance encompassed by a given pair of said corresponding vanes on the circumference of a circle dividing equally the space between said two rotors whereby, regardless of said angular orientation of said rotors with respect to one another, said vanes do not bind against one another.
 2. The variable displacement pump of claim 1 comprising: said drive means being disposed generally between said rotors; said means for maintaining generally constant the circumferential distance encompassed by a given pair of said corresponding vanes comprising pin means extending radially from said drive means and being disposed between each corresponding overlapping pair of vanes and generally contacting both whereby regardless of said angular orientation of said rotors with respect to one another, said vanes contact only said pin means as said rotors are rotated.
 3. The variable displacement pump of claim 2 in which said pin means comprises: a pin having a generally circular cross section.
 4. The variable displacement pump of claim 3 in which said pin is at least as deep as said vaNes in a radial direction.
 5. The variable displacement pump of claim 1 in which said drive means includes a drive ball located generally between said rotors; each said rotors comprising a generally dish-shaped member generally contiguous with said drive ball; said drive ball and said one of said rotors operatively connected thereto including oppositely disposed grooves which open towards one another; each set of oppositely disposed grooves including a bearing means disposed therein whereby said one rotor is fixed against rotation with said ball and thereby rotates with said drive ball when said drive ball is rotated.
 6. The variable displacement pump of claim 5 in which said means for variably adjusting the angular orientation of at least one of said rotors with respect to the other comprises: a generally dish-shaped, regulator movably mounted in said housing and disposed between said one angularly adjustable rotor and said housing; said regulator engaging generally the perimeter of said one angularly adjustable rotor, said one angularly adjustable rotor being rotatable with respect to said regulator and said regulator being fixed against rotation with respect to said housing; control means associated with said regulator for facilitating angular movement of said regulator within said housing whereby the angle of orientation of said one angularly adjustable rotor with respect to the other rotor is varied.
 7. The variable displacement pump of claim 6 in which said drive means includes a drive shaft passing through said one angularly adjustable rotor, through said regulator and through said housing; said one angularly adjustable rotor including an opening for said drive shaft, said opening being larger than the cross section of said drive shaft whereby said one angularly adjustable rotor can be adjusted angularly with respect to said drive shaft; said regulator including an opening larger than the cross section of said drive shaft; said control means including a cam eccentrically mounted on said drive shaft and engaging the perimeter of said opening in said regulator whereby rotation of said cam means with respect to said drive shaft effects angular adjustment of said regulator and said one angularly adjustable rotor.
 8. The variable displacement pump of claim 7 in which said regulator is fixed against rotation with respect to said housing by means of a fin projecting therefrom towards said housing, said housing including a groove receiving said fin, said groove being longer than the length of said fin whereby said fin is free to slide in said groove and said regulator is thereby angularly adjustable.
 9. The variable displacement pump of claim 1 in which said means for variably adjusting the angular orientation of at least one of said rotors comprises: regulator means movably mounted in said housing, disposed between said one angularly adjustable rotor and said housing; said regulator means engaging said one angularly adjustable rotor and being fixed against rotation with respect to said housing, said one angularly adjustable rotor being free to rotate with respect to said regulator means; control means associated with said regulator means for facilitating angular adjustment of said regulator means within said housing whereby the angular orientation of said one angularly adjustable rotor is also adjusted.
 10. The variable displacement pump of claim 9 in which said regulator means comprises: a generally dish-shaped, regulator movably mounted in said housing and disposed between said one rotor and said housing; said drive means including a drive shaft passing through said one angularly adjustable rotor, through said regulator and through said housing; said one angularly adjustable rotor including an opening for said drive shaft, said opening being larger than the cross section of said drive shaft whereby said one angularly adjustable rotor can be adjusted angularly with respect to said drive shaft; said regulator including an opening larger than the cross sectiOn of said drive shaft; said control means including a cam eccentrically mounted on said drive shaft and engaging the perimeter of said opening in said regulator whereby rotation of said cam means with respect to said drive shaft effects angular adjustment of said regulator and said one angularly adjustable rotor.
 11. The variable displacement pump of claim 10 in which said regulator means is a generally dish-shaped, member engaging generally the perimeter of said rotor.
 12. The variable displacement pump of claim 11 in which said drive means includes a drive ball, said rotor being a generally dish-shaped, member which is generally contiguous with said drive ball but which includes a rim projecting away from said drive ball generally at the perimeter of said rotor, said regulator being generally contiguous with the exterior of said rotor and engaging said rim thereof.
 13. The variable displacement pump of claim 12 in which said regulator is fixed against rotation with respect to said housing by means of a fin projecting therefrom towards said housing, said housing including a groove receiving said fin, said groove being longer than the length of said fin whereby said fin is free to slide in said groove and said regulator is thereby angularly adjustable.
 14. The variable displacement pump of claim 1 in which there are means for variably adjusting the angular orientation of both said rotors with respect to one another.
 15. A variable displacement pump comprising: a housing having a pair of ports to provide an inlet and an outlet; a pair of generally oppositely disposed rotors rotatably mounted in said housing; each of said rotors including a plurality of vanes, the vanes on one rotor corresponding to those on the other rotor, said corresponding vanes extending towards one another and generally overlapping one another; drive means operatively connected to at least one of said rotors for effecting rotation thereof; means for variably adjusting the angular orientation of at least one of said rotors with respect to the other whereby the displacement of said pump can be varied; said vanes being shaped such that they maintain generally constant the circumferential distance encompassed by a given pair of vanes on the circumference of a circle dividing equally the space between the two rotors while still maintaining continual contact for effecting a seal between the vanes.
 16. The variable displacement pump of claim 15 in which in each overlapping pair of vanes, one of said vanes is generally flat while the other thereof is convexly shaped, with its convex surface engaging said flat vane.
 17. The variable displacement pump of claim 15 in which both vanes for each overlapping pair of vanes are generally curved in configuration, said vanes slidably engaging one another along the curved surfaces thereof.
 18. The variable displacement pump of claim 15 in which said drive means includes a drive ball located generally between said rotors; each said rotors comprising a generally dish-shaped member generally contiguous with said drive ball; said drive ball and said one of said rotors operatively connected thereto including oppositely disposed grooves which open towards one another; each set of oppositely disposed grooves including a bearing means disposed therein whereby said one rotor is fixed against rotation with said ball and thereby rotates with said drive ball when said drive ball is rotated.
 19. The variable displacement pump of claim 15 in which said means for variably adjusting the angular orientation of at least one of said rotors comprises: regulator means movably mounted in said housing, disposed between said one angularly adjustable rotor and said housing; said regulator means engaging said one angularly adjustable rotor and being fixed against rotation with respect to said housing, said one angularly adjustable rotor being free to rotate with respect to said regulator means; control means associated with said regulator means for facilitating angular adJustment of said regulator means within said housing whereby the angular orientation of said one angularly adjustable rotor is also adjusted.
 20. The variable displacement pump of claim 19 in which said regulator means comprises: a generally dish-shaped, regulator movably mounted in said housing and disposed between said one rotor and said housing; said drive means including a drive shaft passing through said one angularly adjustable rotor, through said regulator and through said housing; said one angularly adjustable rotor including an opening for said drive shaft, said opening being larger than the cross section of said drive shaft whereby said one angularly adjustable rotor can be adjusted angularly with respect to said drive shaft; said regulator including an opening larger than the cross section of said drive shaft; said control means including a cam eccentrically mounted on said drive shaft and engaging the perimeter of said opening in said regulator whereby rotation of said cam means with respect to said drive shaft effects angular adjustment of said regulator and said one angularly adjustable rotor.
 21. The variable displacement pump of claim 20 in which said regulator means is a generally dish-shaped member engaging generally the perimeter of said rotor.
 22. The variable displacement pump of claim 21 in which said drive means includes a drive ball, said rotor being a generally dish-shaped, member which is generally contiguous with said drive ball but which includes a rim projecting away from said drive ball generally at the perimeter of said rotor, said regulator being generally contiguous with the exterior of said rotor and engaging said rim thereof.
 23. The variable displacement pump of claim 22 in which said regulator is fixed against rotation with respect to said housing by means of a fin projecting therefrom towards said housing, said housing including a groove receiving said fin, said groove being longer than the length of said fin whereby said fin is free to slide in said groove and said regulator is thereby angularly adjustable.
 24. The variable displacement pump of claim 15 in which there are means for variably adjusting the angular orientation of both said rotors with respect to one another.
 25. A variable displacement pump comprising: a housing having a pair of ports to provide an inlet and an outlet; a pair of generally oppositely disposed rotors rotatably mounted in said housing; each of said rotors including a plurality of vanes, the vanes on one rotor corresponding to those on the other rotor, said corresponding vanes extending towards one another and generally overlapping one another; drive means operatively connected to at least one of said rotors for effecting rotation thereof; means for variably adjusting the angular orientation of at least one of said rotors with respect to the other whereby the displacement of said pump can be varied; regulator means movably mounted in said housing, disposed between said one angularly adjustable rotor and said housing; said regulator means engaging said one angularly adjustable rotor and being fixed against rotation with respect to said housing, said one angularly adjustable rotor being free to rotate with respect to said regulator means; control means associated with said regulator means for facilitating angular adjustment of said regulator means within said housing whereby the angular orientation of said one angularly adjustable rotor is also adjusted.
 26. The variable displacement pump of claim 25 in which said regulator means comprises: a generally dish-shaped, regulator movably mounted in said housing and disposed between said one rotor and said housing; said drive means including a drive shaft passing through said one angularly adjustable rotor, through said regulator and through said housing; said one angularly adjustable rotor including an opening for said drive shaft, said opening being larger than the cross section of said drive shaft whereby said one angularly adjustable rotor can be adjusted angularly with respect to said drive shaft; said regulator including an opening larger than the cross section of said drive shaft; said control means including a cam eccentrically mounted on said drive shaft and engaging the perimeter of said opening in said regulator whereby rotation of said cam means with respect to said drive shaft effects angular adjustment of said regulator and said one angularly adjustable rotor.
 27. The variable displacement pump of claim 20 in which: said drive means includes a drive ball, said rotor being a generally dish-shaped, member which is generally contiguous with said drive ball but which includes a rim projecting away from said drive ball generally at the perimeter of said rotor, said regulator being generally contiguous with the exterior of said rotor and engaging said rim thereof.
 28. The variable displacement pump of claim 27 in which said regulator is fixed against rotation with respect to said housing by means of a fin projecting therefrom towards said housing, said housing including a groove receiving said fin, said groove being longer than the length of said fin whereby said fin is free to slide in said groove and said regulator is thereby angularly adjustable.
 29. The variable displacement pump of claim 25 in which: there are two said regulators, one for each said rotor, each of said rotors being angularly adjustable by means of said regulators.
 30. A variable displacement pump comprising: a housing having a pair of ports to provide an inlet and an outlet; a pair of generally oppositely disposed rotors rotatably mounted in said housing; each of said rotors including a plurality of vanes, the vanes on one rotor corresponding to those on the other rotor, said corresponding vanes extending towards one another and generally overlapping one another; drive means operatively connected to at least one of said rotors for effecting rotation thereof; said drive means including a drive ball located generally between said rotors; each said rotors comprising a generally dish-shaped member generally contiguous with said drive ball; said drive ball and said one of said rotors operatively connected thereto including oppositely disposed grooves which open towards one another; each set of oppositely disposed grooves including a bearing means disposed therein whereby said one rotor is fixed against rotation with said ball and thereby rotates with said drive ball when said drive ball is rotated; said other rotor being rotatably driven by the interengagement of said vanes of said one rotor which operably engage said vanes of said other rotor.
 31. The variable displacement pump of claim 30 in which there are means for variably adjusting the angular orientation of at least one of said rotors with respect to the other whereby the displacement of said pump can be varied.
 32. The variable displacement pump of claim 31 in which said means for variably adjusting the angular orientation of at least one of said rotors with respect to the other comprises: a generally dish-shaped, regulator movably mounted in said housing and disposed between said one angularly adjustable rotor and said housing; said regulator engaging generally the perimeter of said one angularly adjustable rotor, said one angularly adjustable rotor being rotatable with respect to said regulator and said regulator being fixed against rotation with respect to said housing; control means associated with said regulator for facilitating angular movement of said regulator within said housing whereby the angle of orientation of said one angularly adjustable rotor with respect to the other rotor is varied.
 33. The variable displacement pump of claim 32 in which said drive means includes a drive shaft passing through said one angularly adjustable rotor, through said regulator and through said housing; said one angularly adjustable rotor including an opening for said drive shaft, said opening being larger than the cross section of said drive shaft whereby said one angularlY adjustable rotor can be adjusted angularly with respect to said drive shaft; said regulator including an opening larger than the cross section of said drive shaft; said control means including a cam eccentrically mounted on said drive shaft and engaging the perimeter of said opening in said regulator whereby rotation of said cam means with respect to said drive shaft effects angular adjustment of said regulator and said one angularly adjustable rotor.
 34. The variable displacement pump of claim 33 in which said regulator is fixed against rotation with respect to said housing by means of a fin projecting therefrom towards said housing, said housing including a groove receiving said fin, said groove being longer than the length of said fin whereby said fin is free to slide in said groove and said regulator is thereby angularly adjustable.
 35. A variable displacement pump comprising: a housing having a pair of ports to provide an inlet and an outlet; a pair of generally oppositely disposed rotors rotatably mounted in said housing; each of said rotors including a plurality of vanes, the vanes on one rotor corresponding to those on the other rotor, said corresponding vanes extending towards one another and generally overlapping one another; drive means operatively connected to at least one of said rotors for effecting rotation thereof; means for variably adjusting the angular orientation of each said rotor with respect to the other whereby the displacement of said pump can be varied.
 36. The variable displacement pump of claim 35 in which said means for adjusting for each said rotor comprises: regulator means for each said rotor movably mounted in said housing, disposed between each said rotor and said housing; said regulator means engaging said rotor and being fixed against rotation with respect to said housing, said rotor being free to rotate with respect to said regulator means; control means associated with said regulator means for facilitating angular adjustment of said regulator means within said housing whereby the angular orientation of said rotor is also adjusted.
 37. The variable displacement pump of claim 36 in which said regulator means comprises: a generally dish-shaped, regulator movably mounted in said housing and disposed between said one rotor and said housing; said drive means including a drive shaft passing through said one angularly adjustable rotor, through said regulator and through said housing; said one angularly adjustable rotor including an opening for said drive shaft, said opening being larger than the cross section of said drive shaft whereby said one angularly adjustable rotor can be adjusted angularly with respect to said drive shaft; said regulator including an opening larger than the cross section of said drive shaft; said control means including a cam eccentrically mounted on said drive shaft and engaging the perimeter of said opening in said regulator whereby rotation of said cam means with respect to said drive shaft effects angular adjustment of said regulator and said one angularly adjustable rotor.
 38. The variable displacement pump of claim 37 in which said drive means includes a drive ball, said rotor being a generally dish-shaped, member which is generally contiguous with said drive ball but which includes a rim projecting away from said drive ball generally at the perimeter of said rotor, said regulator being generally contiguous with the exterior of said rotor and engaging said rim thereof; said drive ball and said one driven rotor including oppositely disposed grooves which open towards one another, there being bearing means in said grooves whereby said one driven rotor is fixed against rotation with respect to said drive ball and therefore rotates with said drive ball when said drive ball rotates.
 39. The variable displacement pump of claim 38 in which said regulator is fixed against rotation with respect to said housing by means of a fin projecting therefrom towards said housing, said housing including a groove reCeiving said fin, said groove being longer than the length of said fin whereby said fin is free to slide in said groove and said regulator is thereby angularly adjustable.
 40. The variable displacement pump of claim 36 in which said drive means includes a drive ball, said rotor being a generally dish-shaped, member which is generally contiguous with said drive ball but which includes a rim projecting away from said drive ball generally at the perimeter of said rotor, said regulator being generally contiguous with the exterior of said rotor and engaging said rim thereof.
 41. A variable displacement pump comprising a housing having a pair of ports to provide an inlet and an outlet; a pair of generally oppositely disposed rotors rotatably mounted in said housing; each of said rotors including a plurality of vanes, the vanes on one rotor corresponding to those on the other rotor, said corresponding vanes extending towards one another and generally overlapping one another; drive means operatively connected to at least one of said rotors for effecting rotation thereof; means for variably adjusting the angular orientation of at least one of said rotors with respect to the other, from a point at which said rotors are generally parallel in either direction on either side of this point whereby the displacement of said pump can be varied and whereby the direction of flow of fluid in said pump can be reversed without reversing the direction of rotation of said rotors.
 42. The variable displacement pump of claim 41 in which said means for variably adjusting the angular orientation of at least one of said rotors comprises regulator means movably mounted in said housing, disposed between said one angularly adjustable rotor and said housing; said regulator means engaging said one angularly adjustable rotor and being fixed against rotation with respect to said housing, said one angularly adjustable rotor being free to rotate with respect to said regulator means; control means associated with said regulator means for facilitating angular adjustment of said regulator means within said housing whereby the angular orientation of said one angularly adjustable rotor is also adjusted.
 43. The variable displacement pump of claim 42 in which said regulator means comprises a generally dish-shaped, regulator movably mounted in said housing and disposed between said one rotor and said housing; said drive means including a drive shaft passing through said one angularly adjustable rotor, through said regulator and through said housing; said one angularly adjustable rotor including an opening for said drive shaft, said opening being larger than the cross section of said drive shaft whereby said one angularly adjustable rotor can be adjusted angularly with respect to said drive shaft; said regulator including an opening larger than the cross section of said drive shaft; said control means including a cam eccentrically mounted on said drive shaft and engaging the perimeter of said opening in said regulator whereby rotation of said cam means with respect to said drive shaft effects angular adjustment of said regulator and said one angularly adjustable rotor.
 44. The variable displacement pump of claim 43 in which said regulator means is a generally dish-shaped, member engaging generally the perimeter of said rotor.
 45. The variable displacement pump of claim 44 in which said drive means includes a drive ball, said rotor being a generally dish-shaped, member which is generally contiguous with said drive ball but which includes a rim projecting away from said drive ball generally at the perimeter of said rotor, said regulator being generally contiguous with the exterior of said rotor and engaging said rim thereof.
 46. The variable displacement pump of claim 45 in which said regulator is fixed against rotation with respect to said housing by means of a fin projecting therefrom towards said housing, said housing including a groove receiving said fin, said groove being longer than the lEngth of said fin whereby said fin is free to slide in said groove and said regulator is thereby angularly adjustable, and said groove being positioned such that said regulator can be moved to either side of a point at which said one angularly adjustable rotor is parallel to the other.
 47. The variable displacement pump of claim 41 in which said regulator means is a generally dish-shaped, member engaging generally the perimeter of said rotor.
 48. The variable displacement pump of claim 47 in which said drive means includes a drive ball, said rotor being a generally dish-shaped, member which is generally contiguous with said drive ball but which includes a rim projecting away from said drive ball generally at the perimeter of said rotor, said regulator being generally contiguous with the exterior of said rotor and engaging said rim thereof.
 49. The variable displacement pump of claim 48 in which said regulator is fixed against rotation with respect to said housing by means of a fin projecting therefrom towards said housing, said housing including a groove receiving said fin, said groove being longer than the length of said fin whereby said fin is free to slide in said groove and said regulator is thereby angularly adjustable, and said groove being positioned such that said regulator can be moved to either side of a point at which said one angularly adjustable rotor is parallel to the other.
 50. The variable displacement pump of claim 41 which includes means for maintaining generally constant the circumferential distance encompassed by a given pair of said corresponding vanes on the circumference of a circle dividing equally the space between said two rotors whereby, regardless of said angular orientation of said rotors with respect to one another, siad vanes do not bind against one another. 